What is genetic basis of our intelligence? How to stimulate deep areas of the brain? How to prevent Alzheimer’s disease?  How to slash the cost of treatment of multiple sclerosis? These are some of the questions highlighted in this monthly review of research literature. As usual, while we answer some questions, research studies also dispel some myths and assumption. Whether positive or negative,  the findings always help us to advance further our knowledge of brain and its abilities.

This month, we marked the birthday of Stanley Prusiner, the discoverer of prions – self-replicating proteins behind many neurodegenerative conditions such as Alzheimer’s disease and Parkinson’s disease. Recognising the importance of prions finally put the research aimed at finding the cure for these conditions on the right track.

 THE BEST

New genes for intelligence identified

Intelligence is highly heritable: it is estimated that 80% of our intelligence in adulthood is explained by genetic factors. However, our knowledge of specific genes involved in intelligence is very limited. New study published this month and based on the analysis of genetic data from 78,000 individuals reported 52 genes associated with intelligence, 40 of which are completely novel. Interestingly, many of these genes are also involved in determining other traits such as obesity, BMI, depressive syndromes, Alzheimer’s disease and others.

Brain region responsible for the fear of uncertain future is identified

Many people find it difficult to cope with an uncertain future. Surprisingly, it turned out that this particular behavioural feature closely relates to the size of one specific part of the brain – the striatum. New research suggests that a larger striatum is typically seen in people who have troubles dealing with uncertainties.  The study was done on psychologically healthy individuals, but an enlarged striatum has also been reported to be associated with general anxiety disorder and obsessive compulsive disorder.  Researchers speculate that an enlarged striatum may be linked to a higher risk of developing these disorders later in life.

Non-invasive method of stimulating deep parts of brain

Electric stimulation of deep parts of the brain has proven to be beneficial in treating a number of brain disorders, such as Parkinson’s disease, obsessive compulsive disorder, epilepsy, and depression. However, the approach requires implanting of an electrode directly inside the brain, which involves a risky and costly surgery. A new technique reported this month avoids this problem by using a pair of electrodes located on the surface of the scalp. The method relies on the use of a phenomenon known as temporal interference. This techniques allows the targeted delivery of electrical stimulation to deep areas of brain, such as hippocampus, without stimulating the surface brain area.

New cheap treatment for multiple sclerosis

Antibiotic minocycline, traditionally used as an acne medicine, may provide a safe new method of treating multiple sclerosis (MS), at a fraction of current cost of treating this disease. This drug was developed over 50 years ago. It attracted the attention of researchers studying MS due to its spectrum of anti-inflammatory activities. Phase III trials demonstrated that minocycline slows the progress of disease in patients diagnosed during the early stages of MS.

DNA-based vaccine for Alzheimer’s

Despite our growing understanding of the molecular mechanisms behind the development of Alzheimer’s disease, we still have no single treatment that could cure this condition or stop its progression. An earlier attempt to develop a vaccine preventing the development of Alzheimer’s disease has also failed due to severe side effects. However, new article published this month reports a new promising DNA-based vaccine that inhibits the accumulation of amyloid proteins in animals and shows no side effects observed in previous trials. It remains to be seen if these effects can be reproduced in humans.

Blood-brain barrier and omega-3 fatty acids

Omega-3 fatty acids are well known for their positive effects on general health. Recent findings demonstrate that these compounds are critical players in maintaining the integrity of the blood-brain barrier, the key structure for protecting the brain from various pathogens and toxins. Moreover, researchers demonstrated that permeability of the blood-brain barrier can be regulated by suppressing a protein that transports omega-3 acids to blood vessel cells. Making the barrier more penetrable is advantageous for efficient delivery of drugs when treating patients with various brain disorders.
THE WORST

No stress relief from high doses of tetrahydrocannabinol

Users of cannabis often claim that they use the drug for relaxation and stress relief. More detailed investigation of this effect shows a mixed picture. While experimenting with different doses of tetrahydrocannabinol (THC), the major active substance in marijuana, researchers found that small doses of the compound do indeed reduce stress. However, a slightly higher doses (sufficient to produce a mild “high”) produce an opposite effect and increase anxiety.

Visual cortex develops and matures much slower than assumed

It is traditionally believed that our visual system, including the parts of brain involved in the analysis of visual information, matures within the first few years of life. A new article published this month demonstrates that this assumption is incorrect. Visual cortex continues developing till the late 30s – early 40s. The authors of the article speculate that other parts of the brain may also reach maturity much later in life than currently assumed.

Transcranial direct-current stimulation  does not enhance cognitive training

Transcranial direct-current stimulation () is increasingly used as a method of improving learning abilities. The technique relies on passing weak electric impulses to the brain via electrodes attached to the scalp. Despite the growing popularity of this technique, the evidence in support of its advantages are very limited. A paper published this month casts further doubt on any benefits provided by tDCS. The author reported no improvements of working memory in a large group of subjects using this method, as compared to controls. Furthermore, the analysis of the existing literature on the subject also does not provide any meaningful support to the method. Clearly, further research on tDCS should be done to confirm or rule out the existence of its effects.

Poor sense of smell in humans is a misconception

The superiority of animals sense of smell compared to humans appears to be obvious to most people. After all, we do rely on a dog’s sense of smell for hunting, and it is well known how quickly sharks can detect the slightest smell of blood. However, a new article published this month in Science attempts to dispel the view that the human ability to detect smells is as bad as we are used to thinking. The number of brain cells involved in smell detection in humans is almost the same as in animals, and it is estimated that we can distinguish up to one trillion of different odors. We may lack the degree of specialization demonstrated by many animals in interpreting the information obtained through olfactory system, but the human ability to recognize smells is definitely much stronger than we are accustomed to think.

Women are not better than men at face recognition

It is commonly assumed that women are better  at recognizing and reading faces and correctly interpreting facial expressions. However, a study published this month casts serious doubts on this assumption. Using a series of tests, scientists demonstrated that no detectable difference in facial recognition exists between two genders. Importantly, the neuroimaging of the areas of brain known to be involved in face recognition has shown identical neural activity in both men and women when they were watching a video clip featuring multiple familiar and non-familiar faces.

References:

Suzanne Sniekers, Sven Stringer, Kyoko Watanabe, Philip R Jansen, Jonathan R I Coleman, Eva Krapohl, Erdogan Taskesen, Anke R Hammerschlag, Aysu Okbay, Delilah Zabaneh, Najaf Amin, Gerome Breen, David Cesarini, Christopher F Chabris, William G Iacono, M Arfan Ikram, Magnus Johannesson, Philipp Koellinger, James J Lee, Patrik K E Magnusson, Matt McGue, Mike B Miller, William E R Ollier, Antony Payton, Neil Pendleton, Robert Plomin, Cornelius A Rietveld, Henning Tiemeier, Cornelia M van Duijn, Danielle Posthuma. Genome-wide association meta-analysis of 78,308 individuals identifies new loci and genes influencing human intelligence. Nature Genetics, 2017; DOI: 10.1038/ng.3869

Justin Kim, PhD, Jin Shin, James Taylor, PhD, Alison Mattek, Samantha Chavez, and Paul Whalen, PhD. Intolerance of Uncertainty Predicts Increased Striatal Volume. Emotion, May 2017 DOI: 10.1037/emo0000331

Nir Grossman, David Bono, Nina Dedic, Suhasa B. Kodandaramaiah, Andrii Rudenko, Ho-Jun Suk, Antonino M. Cassara, Esra Neufeld, Niels Kuster, Li-Huei Tsai, Alvaro Pascual-Leone, Edward S. Boyden. Noninvasive Deep Brain Stimulation via Temporally Interfering Electric Fields. Cell, 2017; 169 (6): 1029 DOI: 10.1016/j.cell.2017.05.024

Luanne M. Metz, David K.B. Li, Anthony L. Traboulsee, Pierre Duquette, Misha Eliasziw, Graziela Cerchiaro, Jamie Greenfield, Andrew Riddehough, Michael Yeung, Marcelo Kremenchutzky, Galina Vorobeychik, Mark S. Freedman, Virender Bhan, Gregg Blevins, James J. Marriott, Francois Grand’Maison, Liesly Lee, Manon Thibault, Michael D. Hill, V. Wee Yong. Trial of Minocycline in a Clinically Isolated Syndrome of Multiple Sclerosis. New England Journal of Medicine, 2017; 376 (22): 2122 DOI: 10.1056/NEJMoa1608889

Doris Lambracht-Washington, Min Fu, Pat Frost, Roger N. Rosenberg. Evaluation of a DNA A?42 vaccine in adult rhesus monkeys (Macaca mulatta): antibody kinetics and immune profile after intradermal immunization with full-length DNA A?42 trimer. Alzheimer’s Research & Therapy, 2017; 9 (1) DOI: 10.1186/s13195-017-0257-7

Benjamin J. Andreone, Brian Wai Chow, Aleksandra Tata, Baptiste Lacoste, Ayal Ben-Zvi, Kevin Bullock, Amy A. Deik, David D. Ginty, Clary B. Clish, Chenghua Gu. Blood-Brain Barrier Permeability Is Regulated by Lipid Transport-Dependent Suppression of Caveolae-Mediated Transcytosis. Neuron, 2017; 94 (3): 581 DOI: 10.1016/j.neuron.2017.03.043

Emma Childs, Joseph A. Lutz, Harriet de Wit. Dose-related effects of delta-9-THC on emotional responses to acute psychosocial stress. Drug and Alcohol Dependence, 2017; DOI: 10.1016/j.drugalcdep.2017.03.030

Caitlin R. Siu, Simon P. Beshara, David G. Jones and Kathryn M. Murphy. Development of glutamatergic proteins in human visual cortex across the lifespan. Journal of Neuroscience, May 2017 DOI: 10.1523/JNEUROSCI.2304-16.2017

Jonna Nilsson, Alexander V. Lebedev, Anders Rydström, Martin Lövdén. Direct-Current Stimulation Does Little to Improve the Outcome of Working Memory Training in Older Adults. Psychological Science, 2017; 095679761769813 DOI: 10.1177/0956797617698139

John P. McGann. Poor human olfaction is a 19th-century myth. Science, 2017; 356 (6338): eaam7263 DOI: 10.1126/science.aam7263

Suzanne Scherf, Daniel B. Elbich, Natalie V. Motta-Mena. Investigating the Influence of Biological Sex on the Behavioral and Neural Basis of Face Recognition. eneuro, 2017; ENEURO.0104-17.2017 DOI: 10.1523/ENEURO.0104-17.2017

Image via kennethr/Pixabay.